1. Field of the Invention
The present invention relates to an image processing apparatus, an image processing method, and a computer-readable recording medium for extracting a dark portion area from an intraluminal image acquired by imaging the inside of a lumen.
2. Description of the Related Art
Conventionally, endoscopes are widely used as a medical observation device that is introduced into the inside of a body of an examinee, such as a patient to observe the inside of a lumen in the body. In addition, recently, an easting-type endoscope (capsule endoscope) is developed which has an imaging device, a communication device that transmits image data imaged by the imaging device outside the body in a wireless manner, and the like within a capsule-type casing. Since observation and diagnosis using an image of the inside of the lumen (intraluminal image) that is imaged by such a medical observation device requires an abundance of experience, a medical diagnosis supporting function that supports the diagnosis of a doctor is demanded. As one of image recognition technologies realizing such a function, there is suggested a technology for displaying an image to be focused for diagnosis by automatically detecting an abnormal portion, such as an affected area, from the intraluminal image.
However, the intraluminal image includes an area unnecessary for observation and diagnosis, such as an area (a dark portion area), on which a place that light barely reaches is reflected, for example, represented by the inside of a lumen. Accordingly, in order to detect the above-described abnormal portion, a great importance is put on a preprocessing technology for specifying an area to be focused such as a mucous membrane by performing a process of extracting such an area that is unnecessary for observation and diagnosis. For example, Japanese Laid-open Patent Publication No. 2006-166939 discloses a technology for detecting the presence of a specific body mucous membrane such as an affected mucous membrane within an image without being influenced by an unnecessary area such as a dark portion. According to Japanese Laid-open Patent Publication No. 2006-166939, pixels corresponding to unnecessary areas are excluded based on color information of each pixel, and then the presence of a specific body mucous membrane is detected.